VCE Chemistry Question Thread

[Chocolatepistachio]

Can someone explain the standard addition method and the difference between the standard addition method and use of a calibration curve and calibration standards 

[Chocolatepistachio]

What are the disadvantages of step wise elution over other elution methods 

[beep boop]

Hi All,

Can someone please help me w/ q13 c and q15d?

Much appreciated,
beep boop

[Billuminati]

Hi All,

Can someone please help me w/ q13 c and q15d?

Much appreciated,
beep boop

You should be developing your reasoning of errors since they're asked so frequently by VCAA.

[Chocolatepistachio]

Can someone explain capillary electrophoresis and what the disadvantages are

[Billuminati]

Can someone explain capillary electrophoresis and what the disadvantages are

You'd probably have to take 3rd year analytical chem to know this, this wasn't even taught in 2nd year analytical which is the limit of my knowledge. From its name, it sounds like some kind of separation ie chromatographic technique

[Chocolatepistachio]

What are the benefits of solvent trapping when using splitless injection mode

[Bri MT]

What are the benefits of solvent trapping when using splitless injection mode

Heyo, this is well beyond the scope of VCE chemistry. I know it's quieter, but questions like this would be more suited for the university section (and many of us check recently unread rather than checking individual threads anyway).

[Chocolatepistachio]

For this question why is it less than 5.14
If the stationary phase is more polar then wouldn't it interact more and the retention time increases
polarity of the mobile phase decreases then the polar compound has a lower affinity for the mobile phase so longer retention time

[Billuminati]

For this question why is it less than 5.14
If the stationary phase is more polar then wouldn't it interact more and the retention time increases
polarity of the mobile phase decreases then the polar compound has a lower affinity for the mobile phase so longer retention time

A H2O/acetonitrile mobile phase already indicates a reverse phase chromatographic technique since the mobile phase is polar, implying that the stationary phase and analytes ie ketamine will be relatively non polar. No idea why they said "if the chromatography was reverse phase" as if it wasn't RP-HPLC already.

100% acetonitrile is also polar, but less so than 50% H2O and 50% acetonitrile. Hence ketamine which is implied to be more non polar will elute faster cuz it spends more time in the 100% acetonitrile mobile phase compared to 50% H2O and 50% acetonitrile following the like dissolves like rule. BTW ketamine ain't aliphatic cuz it has a benzene ring, so I don't know what kind of crack the question is on